## MEMORANDUM

TO: Steam Electric ELG Rulemaking Record

FROM: Lydia Lambert, ERG

DATE: April 19, 2013

SUBJECT: Downstream Model Supporting Documentation (DCN SE03891)

ERG is providing technical support to the U. S. Environmental Protection Agency (EPA) for development of revised effluent limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Point Source Category. In support of the development of revised ELGs, ERG developed the following resources to evaluate pollutant concentrations in the downstream receiving water reaches and to calculate the resulting pollutant concentrations in fish tissue. ERG then developed resources to compare the pollutant concentrations to water quality, wildlife, and non-cancer and cancer human health benchmarks to assess the number of improved river miles associated with the regulatory options (Options 1, 2, 3, 4, and 5) under the current profile 1 

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 Downstream Data Preparation Database;

 Downstream Wildlife and Human Health Models;

 Downstream Water Quality General Matrix Database;

 Downstream Wildlife General Matrix Database; and

 Downstream Human Health General Matrix Database.

EPA’s economic contractor, Abt Associates , calculated downstream receiving water concentrations using EPA’s Risk-Screening Envi ronmental Indicators (RSEI) model. ERG then used the downstream receiving water concentrati ons as inputs for the wildlife and human health models described in Section 4.1.2 (Assessm ent of the Surface Water Exposure Pathway), Appendix D (Wildlife Model Methodology), and Appendix E (Human Health Model Methodology) of the Final Environmental Assessment fo r the Proposed Effluent Limitations Guidelines and Standards for the Steam El ectric Power Generating Point Source Category (EA Report) (DCN SE01995). For further details on the RSEI model methodology and assumptions,
see the Benefit and Cost Analysis for the Proposed Effluent Limitations Guidelines and Standards for the Steam Electric Powe r Generating Point Source Category (Benefits and Cost Analysis) (DCN SE03172)

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Abt Associates did not calculate downstream receiving water concen trations for Options 3a, 3b, or 4a, and ERG did not run the wildlife and human health models for these three options.

1 Current profile includes waste streams generated by air pol lution controls that will likely be in operation at steam electric plants at the time EPA takes final action on this rulemaking.

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The methodology used by ERG to estimate dow nstream impacts for these three regulatory options is presented in Appendix G (Methodolog y for Non-Modeled Options) of the EA Report.

The results of the downstream modeling under th e current profile are presented in Section 6.5 (Environmental and Human Health Improvements in Downstream Surface Water) of the EA Report.

A comprehensive listing of the downstr eam model supporting documentation for the current profile is presented in Table 1-1 below. This table provi des the document control number (DCN), title, and abstract of each record item, and identifies wh ether the record item contains Confidential Business Information (CBI). ERG did not conduct downstream modeling for the future profile 2



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Table 1-1. Current Profile Downstream Record Items

DCN Title (Date) Abstract CBI a

SE03537 Downstream Data Preparation for Wildlife and
Human Health Model - Current Profile (101212) Database used to prepare the raw data tables of downstream receiving water concentrations using EPA’s RSEI model for
the Wildlife and Human Health Model. These results are used to populate the Downstream Wildlife and Human
Health Models. Yes

SE03538 Downstream Wildlife and
Human Health Model -
Current Profile - Baseline (101212) Database used to quantify potential impacts to aquatic life, wildlife, and human health do wnstream of the immediate discharge zone for baseline under the current profile. These results are used to populate the Downstream Wildlife Improvements Database and the Downstream Human Health Improvements Database. Yes

SE03539 Downstream Wildlife and
Human Health Model - Current Profile - Option 1 (101212) Database used to quantify potential impacts to aquatic life, wildlife, and human health do wnstream of the immediate discharge zone for Option 1 under the current profile. These results are used to populate the Downstream Wildlife Improvements Database and the Downstream Human Health Improvements Database. Yes

SE03540 Downstream Wildlife and
Human Health Model - Current Profile - Option 2 (101212) Database used to quantify potential impacts to aquatic life, wildlife, and human health do wnstream of the immediate discharge zone for Option 2 under the current profile. These results are used to populate the Downstream Wildlife Improvements Database and the Downstream Human Health Improvements Database. Yes

SE03541 Downstream Wildlife and
Human Health Model - Current Profile - Option 3 (101212) Database used to quantify potential impacts to aquatic life, wildlife, and human health do wnstream of the immediate discharge zone for Option 3 under the current profile. These results are used to populate the Downstream Wildlife Improvements Database and the Downstream Human Health Improvements Database. Yes

2 Future profile includes waste streams generated by future installations of air pollutio n controls at steam electric power plants that may result from some recently promulgated Clean Air Act requirements.

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Table 1-1. Current Profile Downstream Record Items

DCN Title (Date) Abstract CBI a

SE03542 Downstream Wildlife and
Human Health Model - Current Profile - Option 4 (101212) Database used to quantify potential impacts to aquatic life, wildlife, and human health do wnstream of the immediate discharge zone for Option 4 under the current profile. These results are used to populate the Downstream Wildlife Improvements Database and the Downstream Human Health Improvements Database. Yes

SE03543 Downstream Wildlife and
Human Health Model - Current Profile - Option 5 (101212) Database used to quantify potential impacts to aquatic life, wildlife, and human health do wnstream of the immediate discharge zone for Option 5 under the current profile. These results are used to populate the Downstream Wildlife Improvements Database and the Downstream Human Health Improvements Database. Yes

SE03536 Downstream Water Quality Improvements Database -
Current Profile - Baseline and Options (100912) Database used to compare downstream pollutant concentrations in the receiving water, calculated using EPA’s RSEI model, to benchmarks. These results are used to identify the water quality improvements for downstream waters under the evaluated regulatory options. Yes

SE03547 Downstream Wildlife Improvements Database -
Current Profile - Baseline and Options (101512) Database used to calculate the downstream wildlife results (i.e., comparison of fish tissu e concentrations to benchmarks where wildlife may be impact ed) from the downstream
Human Health and Wildlife Model for baseline and the options under the current profile . These results are used to identify the wildlife improvements for downstream waters under the evaluated regulatory options. Yes

SE03544 Downstream Human Health Improvements Database -
Current Profile - Baseline and Option 1 (101212) Database used to calculate the downstream human health
results from the downstream Human Health and Wildlife Model for baseline and Option 1 under the current profile. The results include potential non-cancer and cancer impacts
to human health in the downst ream reaches. These results are used to identify the human health improvements for downstream waters under the evaluated regulatory Option 1. Yes

SE03545 Downstream Human Health Improvements Database - Current Profile - Option 2 and Option 3 (101212) Database used to calculate the downstream human health
results from the downstream Human Health and Wildlife Model for Option 2 and Option 3 under the current profile. The results include potential non-cancer and cancer impacts
to human health in the downst ream reaches. These results are used to identify the huma n health improvements for downstream waters under the evaluated regulatory Options 2 and Option 3. Yes

SE03546 Downstream Human Health Improvements Database - Current Profile - Option 4 and Option 5 (101212) Database used to calculate the downstream human health
results from the downstream Human Health and Wildlife Model for Option 4 and Option 5 under the current profile. The results include potential non-cancer and cancer impacts
to human health in the downst ream reaches. These results are used to identify the water quality improvements for downstream waters under the evaluated regulatory Option 4 and Option 5. Yes

a – Record items containing CBI have been removed from the public record.